Kerr and electro-optic frequency comb generation in integrated lithium niobate devices is provided. In various embodiments, a microring resonator comprising lithium niobate is disposed on a thermal oxide substrate. The microring resonator has inner and outer edges. Electrodes are positioned along the inner and outer edges of the microring resonator. The electrodes are adapted to modulate the refractive index of the microring. A pump laser is optically coupled to the microring resonator. The microring resonator is adapted to emit an electro-optical frequency comb when receiving a pump mode from the pump laser and when the electrodes are driven at a frequency equal to a free-spectral-range of the microring resonator.

The present disclosure discloses a method and apparatus for generating an optical frequency comb. The specific generation method comprises: receiving a pump laser that matches a thermally stable state of a nonlinear optical resonant cavity and causing the pump laser to oscillate in the nonlinear optical resonant cavity, such that a Brillouin gain corresponding to the pump laser coincides with a target longitudinal mode in the nonlinear optical resonant cavity; continuously generating a Brillouin laser at the target longitudinal mode in the case that a pump power of the pump laser exceeds a threshold for generating the Brillouin laser; and generating an optical frequency comb by using the Brillouin laser through a Kerr nonlinear four-wave mixing process. According to the technical solution of the present disclosure, the nonlinear optical resonant cavity with the Brillouin gain can generate an optical frequency comb in its thermally stable region. This optical frequency comb not only has good stability, but also has low quantum noise and narrow linewidth characteristics.

Systems and methods for precision control of microresonator (MR) based frequency combs can implement optimized MR actuators or MR modulators to control long-term locking of carrier envelope offset frequency, repetition rate, or resonance offset frequency of the MR. MR modulators can also be used for amplitude noise control. MR parameters can be locked to external reference frequencies such as a continuous wave laser or a microwave reference. MR parameters can be selected to reduce cross talk between the MR parameters, facilitating long-term locking. The MR can be locked to an external two wavelength delayed self-heterodyne interferometer for low noise microwave generation. An MR-based frequency comb can be tuned by a substantial fraction or more of the free spectral range (FSR) via a feedback control system. Scanning MR frequency combs can be applied to dead-zone free spectroscopy, multi-wavelength LIDAR, high precision optical clocks, or low phase noise microwave sources.

An integrated electro-optic frequency comb generator based on ultralow loss integrated, e.g. thin-film lithium niobate, platform, which enables low power consumption comb generation spanning over a wider range of optical frequencies. The comb generator includes an intensity modulator, and at least one phase modulator, which provides a powerful technique to generate a broad high power comb, without using an optical resonator. A compact integrated electro-optic modulator based frequency comb generator, provides the benefits of integrated, e.g. lithium niobate, platform including low waveguide loss, high electro-optic modulation efficiency, small bending radius and flexible microwave design.

A tunable millimeter-wave signal oscillator includes two phase coherent optical oscillators, a fiber-ring cavity configured to generate two Stokes waves, and a photosensitive element converting the frequency difference of two optical oscillator into a millimeter-wave radiation. A chip-scale form factor millimeter-wave oscillator includes two continuous wave lasers, a plurality of micro-optical-resonators, an optical frequency division mechanism, two optical tunable bandpass filters, and a photosensitive element converting the pulse train of a frequency comb into a millimeter-wave radiation. A millimeter-wave phase noise analyzer includes an optical interferometer, two photosensitive elements, and a fundamental millimeter-wave frequency mixer. A millimeter-wave frequency counter includes an electro-optic optical frequency comb generator, a microwave voltage controlled oscillator, and an optoelectronic phase locked loop. A millimeter-wave electrical spectrum analyzer includes a millimeter-wave phase noise analyzer, a millimeter-wave amplitude detector, a millimeter-wave frequency counter, and a data processing unit.

The present disclosure discloses a method and apparatus for generating an optical frequency comb. The specific generation method comprises: receiving a pump laser that matches a thermally stable state of a nonlinear optical resonant cavity and causing the pump laser to oscillate in the nonlinear optical resonant cavity, such that a Brillouin gain corresponding to the pump laser coincides with a target longitudinal mode in the nonlinear optical resonant cavity; continuously generating a Brillouin laser at the target longitudinal mode in the case that a pump power of the pump laser exceeds a threshold for generating the Brillouin laser; and generating an optical frequency comb by using the Brillouin laser through a Kerr nonlinear four-wave mixing process. According to the technical solution of the present disclosure, the nonlinear optical resonant cavity with the Brillouin gain can generate an optical frequency comb in its thermally stable region. This optical frequency comb not only has good stability, but also has low quantum noise and narrow linewidth characteristics.

A method of generating a terahertz wave and apparatuses performing the method are disclosed. According to an example embodiment, a method of generating a terahertz wave includes outputting a laser comb by modulating a laser output from a laser source based on a linearly modulated frequency of an output that is output from a frequency source, and generating a terahertz wave based on a first comb line and a second comb line selected from the laser comb.

A planar optical resonator capable of parametrically generating frequency combs includes two optical waveguide cores forming inner and outer loops, the resonator having two sections, in which laterally adjacent segments of the cores are resonantly optically coupled to each other at two separate wavelength regions causing separate peaks in the second order dispersion. The resonator sections may be configured to suppress integrated dispersion of the resonator in a broad spectral range favorably for generating a spectrally uniform frequency comb.

Systems and methods in accordance with embodiments of the invention implement electronic frequency-comb detector systems. One embodiment includes an electronic frequency-comb detector, where the electronic frequency-comb detector includes: a frequency-comb generator configured to generate a frequency comb reference signal, and a heterodyne mixer. In addition, the heterodyne mixer is configured to use the frequency comb reference signal to downconvert received millimeter wave (mm-wave) and terahertz (THZ) frequency tones into an intermediate frequency (IF) signal. In a further embodiment, the electronic frequency-comb detector includes an IF amplifier, where the IF amplifier is configured to feed a spectrum analyzer configured to detect a signature of a material under test (MUT).

An ultrahigh-resolution mid-infrared (MIR) dual-comb spectroscopy (DCS) measurement device includes a pump unit, a microring resonator (MRR) unit, a modulation unit, a splitting unit, a testing unit, a signal detection unit, a power balance unit, a reference detection unit and a spectral analysis unit. The measurement method includes: adjusting the laser emitted by the pump unit to the MRR unit; adjusting the modulation unit and performing dual-frequency modulation; generating two sets of MIR optical frequency combs (OFCs) with different repetition rates and splitting the MIR OFCs into the test light and the reference light; performing photoelectric conversion on the test light and injecting the test light to the spectral analysis unit; performing photoelectric conversion on the reference light and injecting the reference light to the spectral analysis unit; and performing Fourier transformation and data processing on test results to obtain absorption spectrum of the to-be-tested sample.